1. Technical Field
The present invention relates to a recording tape cartridge in which a case internally houses a single reel, onto which is wound a recording and reproduction medium, such as a magnetic tape, principally employed by a computer or the like, and to a brake member that is provided at the recording tape cartridge.
2. Related Art
Recording tape cartridges in which a case internally houses a single reel, onto which is wound a recording tape such as a magnetic tape, are provided with a resin brake member that engages with the reel to prevent rotation of the reel inside the case when not in use. When in use, a resin release member lifts up the brake member to release the engagement between the brake member and the reel.
Specifically, the release member rotates together with the reel, making sliding contact with the brake member. Technology is known in which, in order to reduce wear due to friction at the sliding contact location, a steel ball is rotatably provided at the brake member such that the steel ball makes sliding contact with the release member (see for example Japanese Patent Application Laid-Open (JP-A) No. 2000-339911). Technology is also known in which a resin spherical body serving as a release member is provided at a drive device (see for example U.S. Pat. No. 6,279,845).
However, when a steel ball is rotatably provided at the brake member as described in JP-A No. 2000-339911, there is a concern of wear accompanying rotation of the steel ball at locations where the brake member retains the steel ball, as well as a concern regarding losing the ability to retain the steel ball with good precision accompanying increase in the number of times the recording tape cartridge is used.
Moreover, in the technology described in JP-A No. 2000-339911, there is an issue that the steel ball is not easy to install since a base bottom wall extending in the reel radial direction has to be resiliently deformed toward the radial direction outer side when fitting the steel ball into a socket portion of the brake member. There is moreover a concern of a rib that is formed at the socket portion to prevent the steel ball from falling out being damaged or plastically deformed in this fitting operation.
When the rib formed at the socket portion suffers damage or plastic deformation, the retention force of the socket portion with respect to the steel ball decreases, leading to concerns of displacement of the retention position of the steel ball. Namely, there is a concern of the socket portion losing the ability to retain the steel ball with good precision. There are similar concerns on the release member side in U.S. Pat. No. 6,279,845.